I thought the original rider was in a regular straight-ahead lane and people were wanting to squeeze by to turn right, as frequently happens?

If it's a right turn only lane it'd be silly to be in that lane and go straight. But if you are just minding your own business in a straight ahead lane and cars are wanting to sqeeze by to turn right, then you can either be polite and move over for them or not. It's not any different than when you are in a car in the same situation. Sometimes you can move your car a bit to let them by, too, if you feel generous.

Those dual purpose lanes are a bit trickier. It's not like a bike has enough width to effectively block the way. Some idiots will do anything to not be behind you in those kinds of lanes, regardless of any message you are trying to send by your lane position. Most people get it, though.